Heretofore it has been well known to provide a bondable orthodontic appliance for mounting on a tooth, wherein the appliance includes a body and a bonding base attached thereto wherein the body includes an opening for receiving an arm of an auxiliary such as an uprighting spring.
It is also well known to provide bondable orthodontic appliances for mounting on teeth, such as brackets with or without vertical openings or slots. In the profession, the demand for brackets with or without vertical openings or slots is about equal.
It has also been well known to provide metal orthodontic brackets having bodies with vertical slots and with laminated mesh bonding pads or bases attached to the bodies. These laminated mesh bonding pads or bases include a shield or foil of metal laminated to a wire mesh by a sintering process wherein the foil at the periphery is turned over the periphery of the mesh. Such pads or bases are then attached to the brackets.
It is also known to investment cast metal brackets with integral bonding pads or bases wherein such brackets would in some instances include vertical slots or openings.
Further, it is also been known to use a plastic base on a ceramic bracket as disclosed in U.S. Pat. Nos. 5,098,288 and 5,263,859 to facilitate removal of a bracket bonded to a tooth. The latter patent also teaches adhesively securing a bracket to a preformed plastic base where aligning grooves formed in the bracket and the plastic pad define an opening for receiving an auxiliary.
It has also been known as marketed by TP Orthodontics, Inc. of LaPorte, Ind., to provide a ceramic bracket having a ceramic body with a vertical opening or slot for receiving an anchoring arm of an auxiliary and having a heat-cured plastic bonding pad molded to the body of the bracket. These brackets are manufactured under the trademark MXi, which is a trademark of TP Orthodontics, Inc. The bodies of these brackets have been provided with and without vertical openings or slots.
With respect to the use of ceramic brackets by orthodontists, the demand for brackets with vertical slots about equals the demand for brackets without vertical slots, as above mentioned. This requires the manufacturer to have molds for making each of the types of brackets in order to satisfy the demand. From time to time new molds need to be made in order to produce quality brackets, and such molds are quite expensive. With respect to the MXi brackets made by TP Orthodontics, after the bracket body is molded, the wafer or plastic bonding base of a polymer resin is then molded onto the bracket. Accordingly, the polymer resin base is added as a bonding pad following the molding of the ceramic bracket body.
The advent of light-cure adhesive for bonding appliances to teeth has greatly benefitted orthodontists in reducing chair time, easing chairside use by eliminating the need to mix two or more components, allowing unlimited working time because the adhesive does not set up until exposed to light. However, unlike chemical cure adhesives, light-cure adhesives do not cure in the dark. Heretofore, most brackets have metal bonding bases, and when using light-cure adhesive, the curing requires directing light at the base/tooth enamel interface. In order to get optimum curing for the strongest possible bond between metal bonding bases, light must be directed toward the mesial, distal, occlusal and gingival edges of the bonding base to cure the exposed edges of the adhesive. However, the adhesive at the center of the base does not cure because light never reaches the center.